OK, sorry for the whining
After an hour of trying to get the rewrite rule translated for nginx (the server I use), I found out about “try_files”. It’s nifty and provides a partial solution:
location / {
try_files $uri $uri/index.html $uri.html =404;
}
That tries each option in order until it finds a file. Otherwise (last option) it returns a 404. For example for “/foo” it tries “/foo”, then “/foo/index.html”, then “/foo.html” which will work with the Webflow style.
The only problem left is that all the links on the pages use the .html, thus promoting crawlers to index that instead of the desired URLs. I can parse and rewrite all the html files after downloading, but IMO I shouldn’t have to.